Period 7 element

A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with ununoctium, the heaviest element currently discovered. As a rule, period 7 elements fill their 7s shells first, then their 5f, 6d, and 7p shells, in that order, however there are exceptions, such as protactinium.

Properties

All elements of period 7 are radioactive. This period contains the actinides, which contains the heaviest naturally occurring element, californium; subsequent elements must be synthesized artificially. Whilst one of these (einsteinium) is now available in macroscopic quantities, most are extremely rare, having only been prepared in microgram amounts or less. The later, transactinide elements have only been identified in laboratories in batches of a few atoms at a time: of these, ununtrium, ununpentium and those beyond ununhexium have not been recognised by the IUPAC.

Although the rarity of many of these elements means that experimental results are not very extensive, their periodic and group trends are less well defined than other periods. Whilst francium and radium do show typical properties of their respective groups, actinides display a much greater variety of behaviour and oxidation states than the lanthanides. Studies conducted on ununquadium demonstrate some noble gas behaviour, while analogous tests on ununoctium show non-noble gas characteristics. These peculiarities are due to a variety of factors, including a large degree of spin-orbit coupling and relativistic effects, ultimately caused by the very high positive electrical charge from their massive atomic nuclei.

Elements

Chemical element			Chemical series	Electron configuration
87	Fr	Francium	Alkali metal	[Rn] 7s1
88	Ra	Radium	Alkaline earth metal	[Rn] 7s2
89	Ac	Actinium	Actinide	[Rn] 6d1 7s2 (*)
90	Th	Thorium	Actinide	[Rn] 6d2 7s2 (*)
91	Pa	Protactinium	Actinide	[Rn] 5f2 6d1 7s2 (*)
92	U	Uranium	Actinide	[Rn] 5f3 6d1 7s2 (*)
93	Np	Neptunium	Actinide	[Rn] 5f4 6d1 7s2 (*)
94	Pu	Plutonium	Actinide	[Rn] 5f6 7s2
95	Am	Americium	Actinide	[Rn] 5f7 7s2
96	Cm	Curium	Actinide	[Rn] 5f7 6d1 7s2 (*)
97	Bk	Berkelium	Actinide	[Rn] 5f9 7s2
98	Cf	Californium	Actinide	[Rn] 5f10 7s2
99	Es	Einsteinium	Actinide	[Rn] 5f11 7s2
100	Fm	Fermium	Actinide	[Rn] 5f12 7s2
101	Md	Mendelevium	Actinide	[Rn] 5f13 7s2
102	No	Nobelium	Actinide	[Rn] 5f14 7s2
103	Lr	Lawrencium	Actinide	[Rn] 5f14 7s2 7p1 (probably) (**)
104	Rf	Rutherfordium	Transition metal	[Rn] 5f14 6d2 7s2 (probably)
105	Db	Dubnium	Transition metal	[Rn] 5f14 6d3 7s2 (?)
106	Sg	Seaborgium	Transition metal	[Rn] 5f14 6d4 7s2 (?)
107	Bh	Bohrium	Transition metal	[Rn] 5f14 6d5 7s2 (?)
108	Hs	Hassium	Transition metal	[Rn] 5f14 6d6 7s2 (?)
109	Mt	Meitnerium	Transition metal (?)	[Rn] 5f14 6d7 7s2 (?)
110	Ds	Darmstadtium	Transition metal (?)	[Rn] 5f14 6d8 7s2 (?)
111	Rg	Roentgenium	Transition metal (?)	[Rn] 5f14 6d9 7s2 (?)
112	Cn	Copernicium	Transition metal	[Rn] 5f14 6d10 7s2 (?)
113	Uut	Ununtrium	Poor metal (?)	[Rn] 5f14 6d10 7s2 7p1 (?)
114	Uuq	Ununquadium	Poor metal (?)	[Rn] 5f14 6d10 7s2 7p2 (?)
115	Uup	Ununpentium	Poor metal (?)	[Rn] 5f14 6d10 7s2 7p3 (?)
116	Uuh	Ununhexium	Poor metal (?)	[Rn] 5f14 6d10 7s2 7p4 (?)
117	Uus	Ununseptium	Halogen (?)	[Rn] 5f14 6d10 7s2 7p5 (?)
118	Uuo	Ununoctium	Noble gas (?)	[Rn] 5f14 6d10 7s2 7p6 (?)

(?) Prediction

(*) Exception to the Madelung rule.

(**) Probably an exception to the Madelung rule.

Element categories in the periodic table

Metals						Metalloids	Nonmetals			Unknown chemical properties
Alkali metals	Alkaline earth metals	Inner transition metals		Transition metals	Post-transition metals		Other non-metals	Halogens	Noble gases
		Lanthanides	Actinides